title: Heart rate variability in a progressive heart failure model with rapid ventricular pacing.
abstract: BACKGROUND
  Heart rate variability (HRV) is an indicator of autonomic nervous system functionality and a recognized predictor of cardiac death; however, the changes in HRV occurring in progressive heart failure are not fully understood. The purpose of this study was to evaluate the progressive changes of autonomic system activity in progressive heart failure by rapid ventricular pacing in an animal model.
  
  
  METHODS
  Heart failure was induced in 13 mongrel dogs (27.8 +/- 3.7 kg) by rapid ventricular pacing (230 beats/min) for 4 weeks and maintenance of pacing at a reduced rate (190 beats/min) for 2 weeks. Time domain analysis and spectral analysis of HRV were performed with the MemCalc system after 30 minutes of pacing cessation every week. Hemodynamic and echocardiographic data were obtained before and after induction of heart failure.
  
  
  RESULTS
  Cardiac output decreased significantly (3.6 L/min versus 1.6 L/min, P < .001) after 6 weeks of ventricular pacing. Significantly increased were the heart rate (126 beats/min versus 138 beats/min, P < .05), left ventricular end-diastolic pressure (9.1 mm Hg versus 30.9 mm Hg, P < .001), and pulmonary capillary wedge pressure (8.0 mm Hg versus 18.7 mm Hg, P < .001). High-frequency components progressively decreased. Low-frequency components progressively decreased except at 5 weeks after the pacing. A ratio of low- to high-frequency components increased in moderate heart failure and decreased in severe heart failure.
  
  
  CONCLUSIONS
  Changes in the high-frequency component and low-frequency component are important for assessing heart failure in progressive heart failure. Serial follow-up measurements of HRV might be helpful for patients with such disease.
authors.affiliation: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors.forename: Chiyo
authors.initials: C
authors.lastname: Ootaki
authors.forename: Amy
authors.initials: A
authors.lastname: Manzo
authors.forename: Keiji
authors.initials: K
authors.lastname: Kamohara
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popović
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Fukamachi
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Ootaki
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D004285:Dogs; D004562:Electrocardiography / Q000379:methods*; D006333:Heart Failure / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity